1. Field of the Invention
The present invention relates to a system and method employed to electrically stimulate body surfaces so as to potentiate or elicit erotic sensations.
2. Description of the Related Art
Since Luigi Galvani inferred that electric charge could be used to generate a response in excitable tissue in 1771, scientists, researchers and hobbyists have experimented with electricity as a means to evoke various electrophysiologically mediated responses. These responses include, but are not limited to, cardiac pacing and defibrillation, spinal cord stimulation (SCS), deep brain stimulation (DBS), peripheral nerve stimulation (PNS), transcutaneous neural stimulation (TENS), evoked myograms (EMG), erotic stimulation (e-stim), and sensory and motor prosthesis among many others.
The mechanism of action for electrostimulation-mediated sensation generation involves the use of applied electricity to modulate action potentials in the nervous system. Action potentials are depolarizations of neurons which are capable of propagating throughout the body. Inputs to the nervous system are provided by sensory receptors which transduce stimuli such as temperature, pain and touch. Two specific examples of sensory receptors are mechanoreceptors, which transduce mechanical deformation proximal to the receptor, and nociceptors, which transduce the sensation and response to pain. The nerve fibers originating from these sensory receptors terminate at specific points in the central nervous system, which in turn correspond to the signal being sensed. This sensory modality specific linkage is the so-called “labeled line principle.” By means of example, if a touch fiber is stimulated by exciting a touch receptor electrically or in any other way, touch is perceived because the nervous pathway originating from the activated mechanoreceptor terminates in the touch area of the brain. An auditory sensation would not be perceived in this example, as the sensory receptor and pathway is specific for touch not auditory sensation.
Some exemplary mechanoreceptors are shown in FIG. 1. These mechanoreceptors include, but are not limited to, free nerve endings, expanded tip receptors, tactile hair sensors, Pacinian, Meissner's and Krause's corpuscles, Merkel's disks, Ruffini's end-organ, Golgi tendon apparati and muscle spindles. These receptors may be excited in one of several different ways. These methods for excitation may include an appropriate applied electrical stimuli, mechanical deformation or chemical excitation, among others. Each of these receptors are preferentially excited in a slightly different manner. For example, Meissner's corpuscles are selective to light touch at 30-50 Hz. Pacinian corpuscles are more selective to deeper, vibratory touch at 250-350 Hz. Merkel's disks respond to frequencies in the 5-15 Hz range. This non-painful sensory information is carried by large diameter (5 to 12 microns) alpha-beta fibers back to the dorsal horn of the spinal cord and eventually to the brain.
A characteristic of all sensory receptors is that they eventually habituate to some degree to their respective stimuli. When a continuous stimuli is applied, the receptors respond at an initially high rate, followed by a then progressively slower rate until many no longer fire. FIG. 2 shows the habituation of several types of receptors as a function of time, in response to supra-maximal electrical stimulation. The Pacinian corpuscle extinguishes within several hundred milliseconds whereas the Merkel's disk habituates to constant stimulation over the period of hours or days. Receptors with ultra-short habituation times are referred to as phasic receptors, and are responsible for transducing the rate at which change takes place.
A representative electrostimulation signal applied to a body surface so as to potentiate or elicit an erotic sensation is shown in FIG. 3. Biphasic stimulation consisting of a cathodic phase where charge flows out of the target body surface is followed by an anodic phase where charge flows into the body surface. Delivering the cathodic phase first, versus the anodic phase, generally results in lower stimulation amplitude needed to elicit a sensation. The application of a biphasic waveform is generally preferred as it limits undesirable electrochemistry which can result in tissue damage at the electrode-body surface interface. The stimulation is provided at a given site on the body surface with respect to at least a second body surface electrode located somewhere else on the body.
For some, electrostimulation on a body surface may generate a perception of pain. This perception may stem from a host of causes, including one or more of: (a) electrostimulation of sufficient strength to result in muscle contraction; (b) psychosomatic pain in response to the unique sensation of electrostimulation; (c) frank activation of a nociceptive neural circuit. When a nociceptive neural circuit is activated, small diameter neurons such as unmyelinated C fibers less than 2 microns in diameter and myelinated alpha-delta fibers, 2 to 5 microns in diameter, convey the pain sensation to the dorsal horn of the spinal cord and eventually to the brain.
Recognizing that electrostimulation may be used to potentiate or elicit an erotic sensation, some references in the art have elaborated systems and methods which electrically stimulate the genitalia for the purpose of generating sensation therein. These systems and methods are generally designed with limited understanding of the target tissue electroneurophysiology and suffer in turn from habituation to the electrostimulation, numbness and pain in the recipient.
There are a number of patents and publications that teach various components or systems that provide background knowledge and also provide evidence of novelty of the present invention. The teachings and contents of these documents are incorporated herein in entirety by reference, and include the following U.S. patents and published applications: U.S. Pat. No. 3,024,783 by Timcke, entitled “Vibration therapy apparatus”; U.S. Pat. No. 3,294,092 by Landauer, entitled “Therapeutic apparatus”; U.S. Pat. No. 3,295,528 by Masaki, entitled “Electrical therapeutic equipment”; U.S. Pat. No. 3,299,892 by Kendall et al, entitled “Therapeutic pulse generation, control and transmission circuit”; U.S. Pat. No. 3,329,148 by Kendall, entitled “Control of electrotherapeutic apparatus”; U.S. Pat. No. 3,650,276 by Burghele et al, entitled “Method and apparatus, including a flexible electrode, for the electric neurostimulation of the neurogenic bladder”; U.S. Pat. No. 3,735,756 by Richards et al, entitled “Duplex ultrasound generator and combined electrical muscle stimulator”; U.S. Pat. No. 3,893,463 by Williams, entitled “Dual channel stimulator”; U.S. Pat. No. 3,941,136 by Bucalo, entitled “Method for artificially inducing urination, defecation, or sexual excitation”; U.S. Pat. No. 3,952,751 by Yarger, entitled “High-performance electrotherapeutic apparatus”; U.S. Pat. No. 3,983,881 by Wickham, entitled “Muscle stimulator”; U.S. Pat. No. 4,240,437 by Church, entitled “Electric massage apparatus and method”; U.S. Pat. No. 4,279,256 by Bucalo, entitled “Nerve stimulation method”; U.S. Pat. No. 4,319,584 by McCall, entitled “Electrical pulse acupressure system”; U.S. Pat. No. 4,324,253 by Greene et al, entitled “Transcutaneous pain control and/or muscle stimulating apparatus”; U.S. Pat. No. 4,409,565 by Scherer, entitled “Circuit arrangement for producing a low frequency alternating current”; U.S. Pat. No. 4,431,000 by Butler et al, entitled “Transcutaneous nerve stimulator with pseusorandom pulse generator”; U.S. Pat. No. 4,453,548 by Maurer et al, entitled “Method of improving sensory tolerance with modulated nerve stimulator”; U.S. Pat. No. 4,585,005 by Lue et al, entitled “Method and pacemaker for stimulating penile erection”; U.S. Pat. No. 4,620,543 by Heppenstall et al, entitled “Enhanced fracture healing and muscle exercise through defined cycles of electric stimulation”; U.S. Pat. No. 4,640,286 by Thomson, entitled “Optimized nerve fiber stimulation”; U.S. Pat. No. 4,653,479 by Maurer, entitled “Interrupted drive limb motion apparatus”; U.S. Pat. No. 4,690,142 by Ross et al, entitled “Method and system for utilizing electro-neuro stimulation in a bio-feedback system”; U.S. Pat. No. 4,919,138 by Nordenstroom, entitled “Method and apparatus for supplying electric energy to biological tissue for simulating the physiological healing process”; U.S. Pat. No. 4,919,139 by Brodard, entitled “Electrical neuromuscular stimulation device”; U.S. Pat. No. 4,926,879 by Sevrain et al, entitled “Electro-tactile stimulator”; U.S. Pat. No. 5,069,211 by Bartelt et al, entitled “Microprocessor controlled electronic stimulating device having biphasic pulse output”; U.S. Pat. No. 5,070,873 by Graupe et al, entitled “Method of and apparatus for electrically stimulating quadriceps muscles of an upper motor unit paraplegic”; U.S. Pat. No. 5,107,835 by Thomas, entitled “Electrotherapeutic treatment”; U.S. Pat. No. 5,117,826 by Bartelt et al, entitled “Combined nerve fiber and body tissue stimulation apparatus and method”; U.S. Pat. No. 5,183,041 by Toriu et al, entitled “Transcutaneous electric nerve stimulator”; U.S. Pat. No. 5,571,118 by Boutos, entitled “Apparatus for stimulating penile, scrotal, anal vaginal and clitoral tissue”; U.S. Pat. No. 5,702,428 by Tippey et al, entitled “Electrical stimulation for treatment of incontinence and other neuro-muscular disorders”; U.S. Pat. No. 6,047,212 by Gliner et al, entitled “External defibrillator capable of delivering patient impedance compensated biphasic waveforms”; U.S. Pat. No. 6,236,890 by Oldham, entitled “Stimulation of muscles”; U.S. Pat. No. 6,438,418 by Swerdlow et al, entitled “Method and apparatus for reduction of pain from electric shock therapies”; U.S. Pat. No. 6,493,580 by Cansell et al, entitled “Impulses or a series of impulses for defibrillation and device to generate them”; U.S. Pat. No. 6,526,319 by Kobayashi, entitled “Living body stimulating apparatus”; U.S. Pat. No. 6,535,767 by Kronberg, entitled “Apparatus and method for bioelectric stimulation, healing acceleration and pain relief”; U.S. Pat. No. 6,650,943 by Whitehurst et al, entitled “Fully implantable neurostimulator for cavernous nerve stimulation as a therapy for erectile dysfunction and other sexual dysfunction”; U.S. Pat. No. 6,671,546 by Cansell et al, entitled “Impulses or a series of impulses for defibrillation and device to generate them”; U.S. Pat. No. 6,671,557 by Gliner, entitled “System and method for providing percutaneous electrical therapy”; U.S. Pat. No. 6,684,106 by Herbst, entitled “Method and electronic components for multi-functional electrical stimulation systems”; U.S. Pat. No. 7,050,856 by Stypulkowski, entitled “Variation of neural-stimulation parameters”; U.S. Pat. No. 7,133,723 by Yu, entitled “Device for enhancing cell metabolism”; U.S. Pat. No. 7,167,752 by Lin-Hendel, entitled “Electronic electrical and electro-magnetic health enhancement and stimulation device”; U.S. Pat. No. 7,191,014 by Kobayashi et al, entitled “Living body stimulating apparatus”; U.S. Pat. No. 7,333,858 by Killian et al, entitled “Pulse burst electrical stimulation of nerve or tissue fibers”; U.S. Pat. No. 7,584,003 by Zanella, entitled “Apparatus of electro-stimulation and relative data support”; U.S. Pat. No. 7,593,775 by Campos et al, entitled “Sports equipment with resonant muscle stimulator for developing muscle strength”; U.S. Pat. No. 7,689,287 by Han, entitled “Method of aiding smoking cessation”; U.S. Pat. No. 7,890,182 by Parramon et al, entitled “Current steering for an implantable stimulator device involving fractionalized stimulation pulses”; U.S. Pat. No. 7,979,137 by Tracey et al, entitled “System and method for nerve stimulation”; U.S. Pat. No. 8,073,544 by Pless, entitled “Neurostimulator involving stimulation strategies and process for using it”; U.S. Pat. No. 8,165,695 by DiUbaldi et al, entitled “System and method for selectively stimulating different body parts”; Re 43,374 by Kronberg, entitled “Apparatus and method for bioelectric stimulation, healing acceleration and pain relief”; U.S. Pat. No. 8,315,711 by Campos et al, entitled “Resonant muscle stimulator”; 2010/0204624 by Vuillerme et al, entitled “Endo-buccal device for tactile stimulation and actuation”; and 2013/0237750 by Green and granted as U.S. Pat. No. 8,998,796, entitled “Sexual Stimulation Device”.
In addition to the aforementioned U.S. patents and published patent applications, the following additional patents and publications are also incorporated herein by reference: CA 2319525 by Kaczmarek et al, entitled “Tongue placed tactile output device”; EP 1916982 by Freebody, entitled “Skin surface stimulation using a matrix of controlled stimulation elements”; EP 0620025 by Kolen, entitled “Microprocessor-based nerve and muscle stimulator for localized application”; DE 202004017511 by Jobb, entitled “Sex toy with an electrode for erotic stimulation comprises an assembly of 2-core braided wire, latex strip, bent metal rods and Y cables”; WO 2006063461 by Murison, entitled “Electro-mechanical sexual stimulation device”; EP 0897706 by Ardatin, entitled “Vibrator with clitoris stimulator”; Geng, et al, “Impacts of selected stimulation patterns on the perception threshold in electrocutaneous stimulation”, Journal of Neuroengineering and Rehabilitation 2011, 8:9; and Scheibert J., Leurent S., Prevost A., Debregas G. (2009), “The role of fingerprints in the coding of tactile information probed with a biomimetic sensor”, Science, 323(5920): 1503-6. In addition, Webster's New Universal Unabridged Dictionary, Second Edition copyright 1983, is incorporated herein by reference in entirety for the definitions of words and terms used herein.
As taught by Geng et al. incorporated by reference herein above, the primary challenge for any tactile feedback system, including erotic stimulation systems, is the necessity to manage target tissue habituation to sustained stimulation, and to manage electrostimulator adaptation to target tissue impedance changes. The first of these, target tissue habituation to sustained stimulation, has already been discussed herein above with reference to FIG. 2. The second, managing electrostimulator adaptation to target tissue impedance changes, has to do with the efficacy and safety of the electrostimulator responsive to target tissue impedance changes. For exemplary purposes, if the electrostimulator is designed to produce a pulse train having a voltage independent of target tissue impedance, then substantially more current and energy will be delivered to the tissue when there is low impedance. Described another way, if for exemplary purpose the environment is warm and humid, sufficient to cause a person to perspire, then the tissue will have significantly lower impedance than in a cool and dry environment. This means an apparatus functioning properly on a warm and humid day may be completely non-functional on a cool and dry day. In an alternative, if the electrostimulator is instead configured to produce a pulse train having a constant current, then when there is significantly more impedance in the target tissue, such as on a cold and dry day or when the electrode is poorly affixed or in only poor or partial contact, the electrostimulator may ramp the voltage up substantially to maintain the target current flow. This can harm the target tissue as well. As noted, there are many factors that can affect the impedance of the target tissue, including levels of perspiration, extent or pressure of tissue contact, amount and composition of electrode gels or lubricants, and many other factors. Consequently, managing electrostimulator adaptation to target tissue impedance changes is critical and yet very difficult in the prior art.
As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, at least some of the devices and methods disclosed in the patents and publications listed herein above may be modified advantageously in accordance with the teachings of the present invention. The foregoing and other objects, features and advantages, which will now become more readily apparent by referring to the following specification, drawings and claims, are provided by the various embodiments of the present invention.